<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>

    <button>按钮</button>

    <script>
        //创建定时器
        const timeOut = setTimeout(function(){
            alert("hahah")
        },2000)    

        //取消定时器
        const btnObj = document.querySelector("button")
        btnObj.addEventListener("click",function(){
            alert("计时器取消")
            clearTimeout(timeOut)
        })
    </script>
</body>
</html>